Why was southern Okinawa much harder for U.S. forces to capture?

Southern Okinawa proved significantly more difficult for U.S. forces to capture due to the nature of the Japanese defensive strategy, which relied on prepared, fixed positions and the island's natural geography.

The Japanese forces, numbering approximately 60,000, utilized the island’s extensive network of caves and boulders as fortified shelters, which protected them from heavy American bombardment. Because the defenders fought from these prepared positions, they held a distinct tactical advantage, forcing U.S. troops into tedious and costly frontal assaults to clear fortifications one by one.1

The combat in this sector was characterized as positional warfare, where the Japanese maintained a heavily fortified line stretching from Naha to Shuri and Yonabaru. This line repelled numerous attacks, and even after the main defenses were breached, the Japanese continued to resist with great tenacity, often fighting to the death. The intensity of this resistance is illustrated by the slow progress of U.S. forces, who advanced only 4 miles between early April and late May 1945.12